Global thickness distribution maps of the cryptomaria surface cover-layer and cryptomaria basalt, with regions A, B, C, D, E, F, G, and H denoting representative cryptomaria locations. Among them, the basalt and surface cover-layer densities are 3460 and 2225 kg m⁻³, respectively, with a window size of 10°. Panel (a) represents the thickness of the surface cover-layer. Panel (b) shows the thickness of the basalt.